U.S. patent application number 13/455173 was filed with the patent office on 2012-11-01 for hybrid synchronous motors and current-energized synchronous motors suitable for vehicle drives.
This patent application is currently assigned to BRUSA ELEKTRONIK AG. Invention is credited to Andreas Holzner, Anna Mathoy, Arno Mathoy, Eva Mathoy, Verena Mathoy.
Application Number | 20120274168 13/455173 |
Document ID | / |
Family ID | 47073220 |
Filed Date | 2012-11-01 |
United States Patent
Application |
20120274168 |
Kind Code |
A1 |
Holzner; Andreas ; et
al. |
November 1, 2012 |
HYBRID SYNCHRONOUS MOTORS AND CURRENT-ENERGIZED SYNCHRONOUS MOTORS
SUITABLE FOR VEHICLE DRIVES
Abstract
Laminated rotor (21) assemblies for rotating electric machines
such as hybrid synchronous motors (HSM) of vehicle drives, the
rotor plates (26) of which have one or several recesses (29) as a
flux barrier or magnet pocket, which comprise radially innermost
and outermost edge sections as rounded transition regions from and
to edge sections lying therebetween. Each of the rounded transition
regions may be shaped at least approximately respectively according
to a part of a curve (35) of second order. Between adjacent
recesses (29), a respective oblique cross-piece (52) is provided,
the center line (54) of which lies obliquely to the pole axis
(30).
Inventors: |
Holzner; Andreas; (Inzell,
DE) ; Mathoy; Arno; (Grabs, CH) ; Mathoy;
Verena; (Grabs, CH) ; Mathoy; Anna; (Grabs,
CH) ; Mathoy; Eva; (Grabs, CH) |
Assignee: |
BRUSA ELEKTRONIK AG
Sennwald
CH
|
Family ID: |
47073220 |
Appl. No.: |
13/455173 |
Filed: |
April 25, 2012 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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PCT/IB2011/053024 |
Apr 7, 2011 |
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13455173 |
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12675780 |
Feb 27, 2010 |
8198776 |
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PCT/IB08/53462 |
Aug 28, 2008 |
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PCT/IB2011/053024 |
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61363199 |
Jul 9, 2010 |
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60969628 |
Sep 2, 2007 |
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Current U.S.
Class: |
310/156.53 |
Current CPC
Class: |
H02K 1/246 20130101;
H02K 1/276 20130101; H02K 29/03 20130101; H02K 1/2773 20130101 |
Class at
Publication: |
310/156.53 |
International
Class: |
H02K 1/27 20060101
H02K001/27 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 28, 2007 |
DE |
102007040750.7 |
Jul 9, 2010 |
EP |
10169115 |
Claims
1. An electric machine rotor assembly comprising: a rotor piece,
said rotor piece having a central axis, said rotor piece having a
radial extent from said central axis; a first magnet pocket recess
disposed in said rotor piece and transversely to a radius of said
rotor piece, said magnet pocket recess having a major axis
coinciding with a chord segment of a rotor circle delineated by
said radial extent; said magnet pocket recess having a
radially-outer top wall; said magnet pocket recess having a
radially-inner bottom wall; said magnet pocket recess having a
first end closing between said radially-outer top wall and said
radially-inner bottom wall, and said magnet pocket recess having a
second end closing between said radially-outer top wall and said
radially-inner bottom wall; a first flux barrier recess located
proximate to said first end, said first flux barrier recess
separated from said first end by a first oblique crosspiece lying
obliquely at an angle in the range of 10.degree.-50.degree.
relative to a radius of said rotor piece that passes through a
center of said magnet pocket recess, said first flux barrier recess
having a respective upper wall, and said first flux barrier recess
having a respective lower wall; a second flux barrier recess
located proximate to said second end, said second flux barrier
recess separated from said second end by a second oblique
crosspiece lying obliquely at an angle in the range of
10.degree.-50.degree. relative to a radius of said rotor piece that
passes through a center of said magnet pocket recess, said second
flux barrier recess having a respective upper wall, and said second
flux barrier recess having a respective lower wall; a pocket recess
first outer transition region between said radially-outer top wall
and said first end, a pocket recess first inner transition region
between said radially-inner bottom wall and said first end, a
pocket recess second outer transition region between said
radially-outer top wall and said second end, a pocket recess second
inner transition region between said radially-inner bottom wall and
said second end, a first flux barrier upper transition region
between said first flux barrier respective upper wall and said
first oblique crosspiece, a first flux barrier lower transition
region between said first flux barrier respective lower wall and
said first oblique crosspiece, a second flux barrier upper
transition region between said second flux barrier respective upper
wall and said second oblique crosspiece, a second flux barrier
lower transition region between said second flux barrier respective
lower wall and said second oblique crosspiece, each of said
transition regions having a respective profile shape at least
approximately in a respective form of a respective curve of second
order.
2. The electric machine rotor assembly as claimed in claim 1,
wherein: each transition region's profile shape includes a
respective profile shape selected from the group consisting of an
elliptical profile, a parabolic profile, and a higher-order
polynomial profile.
3. The electric machine rotor assembly as claimed in claim 1,
wherein: each transition region's profile shape is a respective
elliptical profile.
4. An electric machine rotor assembly as claimed in claim 1,
further comprising: said rotor piece being produced from an
iron-cobalt alloy.
5. An electric machine rotor assembly as claimed in claim 1,
further comprising: an outer magnet pocket recess disposed in said
rotor piece and transversely to a radius of said rotor piece, said
outer magnet pocket recess having a respective major axis parallel
to the major axis of said first magnet pocket recess that coincides
with a chord segment of a rotor circle delineated by said radial
extent; said outer magnet pocket recess having a respective
radially-outer top wall; said outer magnet pocket recess having a
respective radially-inner bottom wall; said outer magnet pocket
recess having a respective first end closing between its respective
radially-outer top wall and its respective radially-inner bottom
wall, and said outer magnet pocket recess having a second end
closing between its respective radially-outer top wall and its
respective radially-inner bottom wall; a first radially outwardly
lying recess located proximate to said outer magnet pocket's first
end, said first radially outwardly lying recess having a ham-like
or kidney-like contour; and, a second radially outwardly lying
recess located proximate to said outer magnet pocket's second end,
said second radially outwardly lying recess having a ham-like or
kidney-like contour.
6. An electric machine rotor assembly as claimed in claim 5,
further comprising: an outer magnet pocket recess first outer
transition region between said outer magnet pocket recess
radially-outer top wall and said outer magnet pocket recess first
end, an outer magnet pocket recess first inner transition region
between said outer magnet pocket recess radially-inner bottom wall
and said outer magnet pocket recess first end, an outer magnet
pocket recess second outer transition region between said outer
magnet pocket's radially-outer top wall and said outer magnet
pocket's second end, an outer magnet pocket recess second inner
transition region between said outer magnet pocket's radially-inner
bottom wall and said outer magnet pocket's second end, each of said
outer magnet pocket's transition regions having a respective
profile shape at least approximately in a respective form of a
respective curve of second order.
7. The electric machine rotor assembly as claimed in claim 6,
wherein: each respective transition region of said outer magnet
pocket's transition regions includes a respective profile shape
selected from the group consisting of an elliptical profile, a
parabolic profile, and a higher-order polynomial profile.
8. The electric machine rotor assembly as claimed in claim 6,
wherein: each transition region's respective profile shape is a
respective elliptical profile.
9. A laminated rotor for a hybrid synchronous motor comprising: a
plurality of rotor plates; at least one of said plurality of rotor
plates having a respective plurality of recesses therein; at least
one of said plurality of recesses has an innermost edge section,
and said at least one of said plurality of recesses has an
outermost edge section, said innermost and outermost edge sections
being at respective edges thereof in the form of respective rounded
transition regions; at least one of said innermost and outermost
rounded transition regions being configured in either one of a
circular or elliptical segment shape, and each of said innermost
and outermost rounded transition regions being shaped to at least
approximate a respective part of a respective curve of second
order; and, a cross-piece, said cross-piece located between said at
least one of said plurality of recesses and a second one of said
plurality of recesses that is adjacent to said at least one of said
plurality of recesses, said cross-piece disposed to have a center
line lying oblique at an angle in the range of
10.degree.-50.degree. relative to a rotor pole axis.
10. The laminated rotor for a hybrid synchronous motor as claimed
in claim 9, wherein: the angle is 30.degree..
11. The laminated rotor for a hybrid synchronous motor as claimed
in claim 9, wherein: said plurality of rotor plates are produced
from an iron-cobalt alloy.
12. The laminated rotor for a hybrid synchronous motor as claimed
in claim 11, wherein: said iron-cobalt alloy has a proportion of
50% cobalt and 50% iron.
13. The laminated rotor for a hybrid synchronous motor as claimed
in claim 9, wherein: each respective curve of second order in said
rounded transition regions is elliptical.
14. The laminated rotor for a hybrid synchronous motor as claimed
in claim 9, wherein: each respective curve of second order in said
rounded transition regions approximates a respective ellipse.
15. The laminated rotor for a hybrid synchronous motor as claimed
in claim 9, wherein: each respective curve of second order in said
rounded transition regions is parabolic.
16. The laminated rotor for a hybrid synchronous motor as claimed
in claim 9, wherein: each respective curve of second order in said
rounded transition regions is configured according to a polynomial
of higher order.
17. A laminated rotor for a hybrid synchronous motor as claimed in
claim 9, further comprising: at least one outwardly-lying recess of
said plurality of recesses, said at least one outwardly-lying
recess having a kidney-like interior contour.
18. An electric machine rotor assembly comprising: a rotor piece,
said rotor piece having at least one salient pole, said at least
one salient pole having a shank, said shank having a radial shank
axis, and said at least one salient pole having a shoe; a magnetic
flux barrier in said first salient pole, said magnetic flux barrier
including a radially-extending longitudinal slot in said at least
one salient pole, said radially-extending longitudinal slot having
a central slot axis coincident with said shank axis, said
radially-extending longitudinal slot having a first lateral side
surface, said radially-extending longitudinal slot having a second
lateral side surface, the distance between said first and second
lateral side surfaces defining a slot width; a radially-outermost
edge section of said radially-extending longitudinal slot, said
radially-outermost edge section located at a radially outer end of
said radially-extending longitudinal slot; said radially-outermost
edge section including a curved outermost transition region; a
radially-innermost edge section of said radially-extending
longitudinal slot, said radially-innermost edge section located at
a radially inner end of said radially-extending longitudinal slot;
said radially-innermost edge section including an innermost
transition region; a bridge spanning the slot width and connected
to said first and said second lateral side surfaces, said bridge
dividing said radially-extending longitudinal slot into a first
radially-inner slot portion and a second radially-outer slot
portion; said first slot portion having a respective outer
transition region; said second slot portion having a respective
inner transition region; and, a permanent magnet in said first slot
portion, said permanent magnet configured to generate flux
saturating said bridge to create high resistance for further
magnetic flux in said bridge and reduce magnetic conductivity of
said bridge so as to extend the effect of said magnetic flux
barrier to a total region of a longitudinal axis of said first
pole, said magnet having a direction of magnetization tangential
with respect to a rotational direction of said rotor.
19. The electric machine rotor assembly as claimed in claim 18,
wherein: said curved outermost transition region has profile shape
at least approximately in form of a curve of second order; and,
said innermost transition region is curved.
20. The electric machine rotor assembly as claimed in claim 19,
wherein: said outer transition region of said first slot portion is
curved with profile shape at least approximately in the form of a
curve of second order; and, said inner transition region of said
second slot portion is curved with profile shape at least
approximately in the form of a curve of second order.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application claims benefit as a C-I-P
continuation-in-part of copending U.S. application Ser. No.
12/675,780 filed on Feb. 27, 2010 as a 35 U.S.C. 371 national stage
entry of PCT International App. No. PCT/1B2008/053462 filed on Aug.
28, 2008, claiming benefit of priority to German (DE) application
no. 102007040750.7 filed on Aug. 28, 2007, and also claiming
benefit of priority as a non-provisional of U.S. provisional
application No. 60/969,628 filed on Sep. 2, 2007; the present
application also claims benefit as a C-I-P continuation-in-part of
copending PCT International App. No. PCT/182011/053024 filed on
Jul. 7, 2011, claiming benefit of priority to European (EPO)
application no. EP10169115 filed on Jul. 9, 2010, and also claiming
benefit of priority as a non-provisional of U.S. provisional
application No. 61/363,199 filed on Jul. 9, 2010; the entireties of
parent U.S. application Ser. No. 12/675,780 and of PCT
International Application No. PCT/1B2008/053462, as well as the
entireties of parent PCT International App. No. PCT/182011/053024
and of European (EPO) application no. EP10169115 and U.S.
provisional application No. 61/363,199 are all expressly
incorporated herein by reference in their entireties and as to all
their respective parts, for all intents and purposes, as if all set
forth identically in full herein.
FIELD OF THE INVENTION
[0002] The present invention relates to hybrid synchronous motors
and to current-energized synchronous motors which are suitable for
vehicle drives. The invention also relates to laminated rotors for
rotating electric machines and for highly stressed hybrid
synchronous motors (HSM) of vehicle drives. Furthermore, in aspects
the invention relates to special configurations of the geometries
of rotor plates in electric motors, usable, for example, to drive
electric vehicles.
PRIOR ART
[0003] Since the mid 90's of the previous century, automobile
manufacturers and designers were increasingly concerned with hybrid
drives for cars and sports cars as well as commercial vehicles. The
hybrid drive combines an internal combustion engine with an
electric motor (and optionally with a flywheel). If a small
internal combustion engine (range extender) is used only for power
generation for the main electric drive, the term series hybrid is
used.
[0004] Furthermore, since battery technology has shown significant
progress for some years, battery electric vehicles (BEVs) are also
experiencing a new revival.
[0005] In the case of vehicle drives where the electric motor
provides a significant part of the propulsion power, or such a
motor is the sole drive unit, the power output is intended to take
place in wide speed and load range with as high an efficiency as
possible.
[0006] According to the prior art, the asynchronous motor (ASM), a
particular design of the permanent-magnet synchronous motor (PSM),
and the switched reluctance motor (SRM) are distinguished in
particular here. The preferred design of the PSM is based on the
position of the magnets in the interior of the rotor (internal
permanent magnet motor IPM). Considering the SRM, reference
DE-A-10207267 describes a reluctance motor having a rotor which
consists of a multiplicity of laminated segments which are joined
via non-magnetic connecting elements to result in a unit. The
connecting elements act as flow barriers. Non-magnetic connecting
elements are, as a rule, more expensive than connecting elements of
standard steel or have to be made with larger dimensions in order
to achieve the same strength values as steel.
[0007] Considering synchronous reluctance motors (SyR), reference
DE-A-10004175 describes a synchronous reluctance motor having
continuous flow barriers. Synchronous reluctance motors (SyR) which
are operated with three-phase currents and have a stator similar to
that of asynchronous motors are suitable in practice, owing to
their simple and robust design (no rotor windings or magnets), for
economical industrial drives having a stator diameter of from 150
to 400 mm. Disadvantages are the relatively low torque density in
relation to other motor types and a poor power factor, which
significantly complicates their use in the vehicle and therefore
limits them to stationary applications.
[0008] Considering sine-wave motors, according to earlier research
(i.e., the final report of "Antriebsentwicklung [Drive
development]" at www.brusa.biz), an advantage of sine-wave machines
is their constant torque output over the angle of rotation and the
low noise development from harmonic fields relative to square-wave
motors. This also manifests itself in a constant power uptake from
the power source (battery or motor inverter).
[0009] If the motor inverter takes its power directly from a
battery (battery link), the harmonic fields would, in the case of
square-wave motors, result in alternating loads which cause
additional losses at the internal resistance of the battery. Since
the sine-wave motors have no harmonic fields and thus achieve a
constant power uptake over the angle of rotation, they also cause
no additional losses at the internal resistance of the supply
battery.
[0010] In the narrower choice for a main drive system in which the
motor inverter takes its power directly from a battery, types
having a sinusoidal air-gap field distribution, such as the
asynchronous motor (ASM) and the internal permanent magnet
synchronous motor (IPM), are therefore particularly suitable,
according to the prior art.
[0011] Considering current-energized synchronous motors, as is
known, the current-energized synchronous motor (CSM) has a similar
stator in comparison with other sine-wave motors. However, the
rotor is provided with pronounced poles (non-salient poles or
salient poles) with which rotor windings through which direct
current flows are coordinated. In current-energized synchronous
motors, the energizer power in the rotor must therefore be fed from
the outside. The transmission can take place in a non-contact
manner (via transformer) in large machines. In the case of smaller
motors for vehicle drives, which have a stator diameter from 150 mm
to 400 mm, and in the case of those in which a large dynamic range
of the rotor current regulation is required, it takes place via
brushes and slip rings. Thus, the CSM, together with the direct
current motor (DCM) are among the brush-type motors in which power
transmission takes place via brushes to the rotor.
[0012] A reference to some basic properties of all synchronous
motors may prove helpful to readers. The rotor of every synchronous
motor rotates synchronously with the field of the stator current.
If the rotor cannot rotate with the stator frequency, or the stator
field cannot adapt to the rotor position, the asynchronous
superposition of the rotor and stator fields produces only pendulum
moments. When they are used as a vehicle drive, all types of
synchronous motors therefore require, in principle, a frequency
inverter controlled via the rotor position.
[0013] Considering further the basic properties of conventional
current-energized synchronous motors, with dynamic energizing,
current-energized synchronous motors achieve 2.5 times their
nominal moment for about 30 seconds and up to 4 times their nominal
moment for about 5 seconds. With their short-term moment, they
surpass permanent-magnet synchronous motors of the same size in
most cases. The difference is pronounced particularly when a
comparison is made with synchronous motors having buried magnets
(IPM). In these, the magnets are inserted into slots of the rotor
lamellae.
[0014] Regarding power transmission via brushes in the CSM,
brush-type motors were frequently also not considered because,
according to the prevailing argumentation and conventional wisdom,
this technology would be difficult to market in an innovative
product, and furthermore, lifetime limitations existed due to the
mechanical brush wear and were to be feared.
[0015] As part of a general prejudice, frequently a sufficient
distinction is not made between the commutator of a direct current
motor (DCM) and the comparatively simple slip ring of a
current-energized synchronous motor (CSM). While the total motor
power has to be transmitted to the rotor via the commutator in the
case of a DCM, the energizer power to be transmitted to the slip
ring of the CSM is only in the low one-digit percentage range of
the total motor power. In the case of the CSM, as in the case of
all other synchronous motors for vehicle drives, the actual
electrical motor power is transmitted to the stator via the
frequency inverter.
[0016] Exploring some of the disadvantages of the CSM according to
the prior art, it should be understood that the torque of a
current-energized synchronous motor that is operated without
energizing (emergency torque) arises exclusively from the
reluctance. The reluctance is a dimensionless variable and is
determined by the ratio of the inductance of the longitudinal axis
Ld to the inductance of the transverse axis Lq. In salient-pole
motors, Ld>>Lq, Ld, the longitudinal inductance, being
determined mainly by the air gap, and Lq, the transverse
inductance, being determined mainly by the pole geometry.
[0017] Thus, if, in a current-energized synchronous motor, the
energizing fails, only about a one-quarter of the nominal moment
can be established in the case of conventional salient-pole motors,
and no moment at all in the case of non-salient-pole motors. This
may lead to dangerous driving situations under certain
circumstances.
[0018] Poor or lacking emergency running properties therefore
constitute a further reason why those skilled in the art believed
the current-energized synchronous motor (CSM) to be substantially
unsuitable as a vehicle drive (i.e., for example the final report
cited above).
[0019] Considering the prior art further, an electric machine is
known from publication WO01/48890A1, in which the stator or the
rotor has radial tooth modules/poles which are separated from each
other. In order to increase the reluctance, each tooth module/pole
is provided with a reluctance barrier which is constructed as a
radial and axially extended gap in the pole shoe.
[0020] As is known, the electric motors in the main drive of
electric cars or hybrid cars often operate up to rotation speeds of
approximately 12000 rpm. These high rotation speeds bring about
very great centrifugal forces on the periphery. Considering the CSM
in this context, originally, such current-excited synchronous
motors or generators were employed for large motors or generating
plants, where the rotation speeds are a fraction of the
above-mentioned value. The current-excited synchronous motor
differs from the other types of motor used hitherto in an electric
car (e.g. asynchronous and permanent magnet synchronous motors)
most significantly by a wound and current-excited rotor.
[0021] Given the very high centrifugal forces which act on the pole
caps and are produced not least by the weight of the copper
windings, in the new application for electric cars the poles/pole
shoes or plate stacks of the CSM rotor are particularly highly
stressed. Owing to the high centrifugal forces, that are produced,
inter alia, by the winding, and that act with leverage force on the
pole caps, high notch stresses occur in the region of slots acting
as a flux barrier, namely at the geometric transitions from the
horizontal into the vertical. Furthermore, with the configuration
of conventional roundings (circular in shape), enormous stress
peaks also occur, and namely at the transitions from the circular
rounding to the straight line. Nowadays, these stress peaks
restrict the possibility for further development of the rotor
geometry in a CSM, or prevent high rotation speeds. Conventional
methods, such as for example the application of Kevlar cages,
welded or screw constructions or the like which are intended to
increase the stability of the rotor, however, have a
performance-reducing effect.
[0022] Similar effects also occur, however, in known hybrid
synchronous motors (HSM) employed for the main drive in the field
of automobiles, in which HSMs recesses are provided for buried
magnets and/or punched-out flux barriers are provided.
[0023] Another problem in the rotor geometry of the conventional
CSMs lies in that the plate stacks of the rotor, likewise under the
rotation speed-induced centrifugal forces, with identical
dimensioning lift themselves earlier from the shaft than in
comparable electric motors with closed rotor plate stacks. The
effect of the lifting from the shaft consequently likewise limits
the possible rotation speed. While the lifting effect is less
pronounced in machines with a closed pole structure (e.g. HSM), it
remains considerable.
[0024] Therefore, an improved lifting behaviour, i.e., less easy
releasing of the plate stack from the shaft, is also desirable. The
lifting behaviour of the rotor plates could theoretically be
influenced by a greater interference fit between shaft and rotor
plate. However, the stress on the plate geometry would be
additionally increased in the region of the radial slits, a
consequence which is not desirable for the reasons previously
mentioned. Therefore, the effects of lifting and notch stresses or
respectively increased contact pressure between rotor plate stack
and shaft, and increased notch stress play against each other in a
disadvantageous manner.
[0025] Thus, it could be defined as a superordinate objective, to
find a rotor structure that has no centrifugal force-induced
problems at high rotation speeds (e.g. approximately 12000 rpm).
Considering prior reference US20070096578A1, it discloses a rotor
for electric machines. However, this solution deals expressly only
with the edge paths of the recesses of the rotor plate immediately
adjoined by the outer rotor periphery, wherein exclusively the
curved end part of the recess is configured circularly or, if
applicable, elliptically. According to prior US20100045121A1, a
cobalt alloy was used for the magnet circuits, to increase the
magnetic saturation in electric motor construction.
[0026] None of the indicated previously known technologies
satisfactorily resolved the problems which are posed.
SUMMARY OF THE INVENTION
[0027] In aspects, the invention relates to the context of solving
the problem of creating an improved rotor geometry, by which the
above-mentioned disadvantages of the prior art may be reduced or
eliminated, i.e., by which on the one hand the stress peaks, in
particular the notch stresses in the rotor--despite high
centrifugal forces--may be significantly reduced. On the other
hand, through the invention also the lifespan and the torque of the
rotor or of the electric motor are to be increased, and therefore
also the lifting behaviour is to be positively influenced, or
reduced.
[0028] In versions, the invention proceeds from a laminated rotor
for rotating electric machines, in particular for a hybrid
synchronous motor of vehicle drives, the rotor plates of which have
one or several recesses as flux barrier or magnet pocket. The
radially innermost and outermost edge sections of these recesses
(rounded transition regions) comprise edge sections lying
therebetween, wherein at least one of these transition regions is
configured in a circular or ellipse shape. According to the
invention, each of the rounded transition regions may be shaped at
least approximately respectively according to a part of a curve of
second order, on the other hand between the adjacent recesses in
each case an oblique cross-piece is provided, the centre line of
which lies obliquely to a pole axis and forms here with the pole
axis preferably an angle of approximately 20.degree.-50.degree., in
particular 30.degree..
[0029] The term "curve of second order" is to be understood in this
application to mean, both in the description and also in the
claims, a geometric figure of a curve which can be designated as a
conic section, and which is configured elliptically, parabolically
or hyperbolically (i.e., not circularly or angularly).
[0030] This rotor plate geometry is suitable in particular for a
fast-running HSM or CSM.
[0031] In the CSM, the rotor comprises at least two rotor poles,
each with an exciter winding and in each rotor pole at least one
magnetic flux barrier in the form of a radial slit. In the HSM, per
rotor pole at least one magnet is housed in a magnet pocket and the
lamination also has at least one flux barrier.
[0032] Our calculations [by means of the Finite Element Method
(FEM)] and tests confirmed that the shape of an ellipse in the
recess transition region involves the least stresses. In the
opinion of the inventors, this is attributable to the continuous
alteration of the distance from the intersection of the main axis
of the ellipse. (This corresponds to a continuous alteration of the
radius). By systematic determination of height and width, the
ellipse can be optimized geometrically with respect to as minimal a
notch stress as possible. As the use of two cooperating circular
roundings with different radii represents a good approximation to
the ellipse, thereby a distinct improvement compared to a pure
circular rounding can already be achieved. Through the elliptical
configuration of the transition regions of the recesses, the
lifespan of the rotor is increased and the risk of fracture induced
by centrifugal force is reduced.
[0033] An effective deflection of the flux of force desirably takes
place in the transition region or, respectively, a reduction of the
notch effect, which does not even allow stress peaks to occur in
the dangerous zone at all. Through the use of the ellipse shape
with its continuous distance increase, this takes place in a
particularly harmonious manner. (The term "distance" is to be
understood in each case to mean a distance from the intersection of
the main axis of the ellipse.) The condition for fulfilling the
function of the continuous distance increase could also be
designated as "distance gradient". This continuous distance
increase as a condition could, however, in addition to the ellipse,
also be fulfilled by parabola (quadratic function), polynomials of
higher order, or as an approximation to the ellipse by two radii
continuing tangentially into each other, with a different
value.
[0034] This part of the invention therefore basically may be used
advantageously in all electric motors with radial slits, magnet
pockets and/or other recesses, in which notch stresses occur. In
this respect, the invention is not merely restricted to CSM or HSM,
but rather it can be used expediently in any rotor geometry having
recesses.
[0035] In the preferred exemplary version, alternatively to
iron-silicon plates, at least the rotor plates, to increase the
rotor torque that is achievable, are produced from an iron-cobalt
alloy, preferably with a proportion of 50% cobalt and 50% iron.
Through this measure, the torque e.g. of a HSM may therefore be
further increased and hence the power density may be increased
significantly.
[0036] In an exemplary version of a CSM, the radial slot is
divided--in its longitudinal axis--by a transversely arranged
bridge into two or several regions, wherein the radially inner
first slit part is configured as a first flux barrier, if
applicable to receive a permanent magnet, and the radially outer
second slit part is configured as a second flux barrier, if
applicable also to receive a permanent magnet. Through the
permanent magnet, the rotor iron of the rotor plates--at the
bridges or respectively at the remaining connection sites--is
saturated, so that these regions for the magnetic flux act as a
division of the pole. Thereby, the effect of the magnetic field
lines can be optimized in the rotor pole.
[0037] In an expedient version, at least the radially inner end of
the two slit parts for the continuous distance increase is
configured elliptically and/or parabolically and/or with two radii
continuing into each other tangentially. The radially outer end of
the first slit part can also be configured elliptically and/or
parabolically and/or with two radii continuing into each other
tangentially as an approximation to an ellipse.
[0038] If applicable--alternatively or additionally--the radially
outer slit part may also receive a permanent magnet.
[0039] In some preferred exemplary versions of the invention, the
curves of second order in the transition regions in all recesses
and contour sections of the rotor plate may be configured
elliptically or approximately to an ellipse. In additional
preferred exemplary versions, there is a rotor piece having at
least one salient pole that has a shank, said shank having a radial
shank axis, and said at least one salient pole having a shoe. There
is a radially-extending longitudinal slot in said at least one
salient pole, said radially-extending longitudinal slot having a
central slot axis coincident with said shank axis, said
radially-extending longitudinal slot having first and a second
lateral side surfaces, the distance between said first and second
lateral side surfaces defining a slot width. Furthermore, there is
a radially-outermost edge section of said radially-extending
longitudinal slot, said radially-outermost edge section located at
a radially outer end of said radially-extending longitudinal slot.
This radially-outermost edge section includes a curved outermost
transition region having profile shape at least approximately in
form of a curve of second order. A radially-innermost edge section
of said radially-extending longitudinal slot is located at a
radially inner end of said radially-extending longitudinal slot.
This radially-innermost edge section includes a curved innermost
transition region having profile shape at least approximately in
form of a curve of second order. A bridge spanning the slot width
and connected to said first and said second lateral side surfaces
divides said radially-extending longitudinal slot into a first
radially-inner slot portion and a second radially-outer slot
portion; said first slot portion having a respective curved outer
transition region having profile shape at least approximately in
form of a curve of second order. The second slot portion has a
respective curved inner transition region having profile shape at
least at least approximately in form of a curve of second order,
and a permanent magnet is in said first slot portion. This
permanent magnet generates flux saturating said bridge to create
high resistance for further magnetic flux in said bridge and to
reduce magnetic conductivity of said bridge, so as to extend the
effect of said magnetic flux barrier to a total region of a
longitudinal axis of said at least one salient pole. The second
radially-outer slot portion is preferably an empty (vacant) space
flux barrier, or may have a second permanent magnet therein.
[0040] Preferably, the recesses in the rotor poles are configured
as radial slots, wherein the curve of second order is arranged as
an ellipse in the radial slit tangentially and symmetrically. Here,
a main axis of the tangential ellipse, which defines the rounding,
can preferably be configured greater by 40-60% than a width of the
radial slit, and a secondary axis of the ellipse can preferably be
configured smaller by 70-80% than the width of the slit.
[0041] If applicable, however, the curves in the transition regions
may be configured parabolically, hyperbolically, therefore
according to a polynomial of higher order (third or higher order),
or with two radii continuing tangentially into each other with a
different value--as an approximation to the ellipse--, in order to
achieve an improvement compared with conventional pure radii in the
transition regions. Thus, in the aforementioned additional
preferred exemplary versions, said curved outermost transition
region's profile shape, and said curved innermost transition
region's profile shape, and said curved outer transition region's
profile shape, and said curved inner transition region's profile
shape, each may include a respective profile shape selected from
the group consisting of an elliptical profile, a parabolic profile,
and a higher-order polynomial profile.
[0042] In yet additional preferred exemplary versions of the
invention, there is a rotor piece having at least one salient pole
that has a shank, said shank having a radial shank axis, and said
at least one salient pole having a shoe. A radially-extending
longitudinal slot in said at least one salient pole has a central
slot axis coincident with said shank axis. This radially-extending
longitudinal slot has first and second lateral side surfaces, the
distance between said first and second lateral side surfaces
defining a slot width. A radially-outermost edge section of said
radially-extending longitudinal slot is located at a radially outer
end of said radially-extending longitudinal slot, and said
radially-outermost edge section includes a curved outermost
transition region having profile shape at least approximately in
form of a curve of second order. Furthermore, a radially-innermost
edge section of said radially-extending longitudinal slot is
located at a radially inner end of said radially-extending
longitudinal slot. This radially-innermost edge section includes a
curved innermost transition region having profile shape at least
approximating an ellipse perimeter formed by an ellipse having
major diameter of length greater than said slot width by a range of
40-60% and having minor diameter length smaller by a range of
70-80% than said slot width. There is a bridge spanning the slot
width and connected to said first and said second lateral side
surfaces, this bridge dividing said radially-extending longitudinal
slot into a first radially-inner slot portion and a second
radially-outer slot portion. A permanent magnet is located in said
first slot portion. It is further advantageous if permanent magnet
generates flux saturating said bridge to create high resistance for
further magnetic flux in said bridge and reduce magnetic
conductivity of said bridge so as to extend the effect of said
magnetic flux barrier to a total region of a longitudinal axis of
said at least one salient pole. In turn, the second radially-outer
slot portion is either preferably an empty-space flux barrier, or
may have a second permanent magnet therein.
[0043] In variations of these additional preferred exemplary
versions of the invention, it may be additionally advantageous
configure said curved outermost transition region's profile shape
to include a profile shape selected from the group consisting of an
elliptical profile, a parabolic profile, and a higher-order
polynomial profile. Or, to configure said first slot portion to
have a respective curved outer transition region having profile
shape at least approximating a respective ellipse perimeter formed
by a respective ellipse having a respective major diameter of
length greater than said slot width by a range of 40-60% and having
a respective minor diameter length smaller by a range of 70-80%
than said slot width. Or, to configure said second slot portion to
have a respective curved inner transition region having profile
shape at least approximating a respective ellipse perimeter formed
by a respective ellipse having a respective major diameter of
length greater than said slot width by a range of 40-60% and having
a respective minor diameter length smaller by a range of 70-80%
than said slot width. In additional variations, it may be afford
advantage to configure the respective minor diameter of said
respective ellipse perimeter of said curved outer transition region
of said first slot portion to be smaller than said minor diameter
of said curved innermost transition region's ellipse perimeter, or
additionally, to configure said respective minor diameter of said
respective ellipse perimeter of said curved inner transition region
of said second slot portion to be smaller than said minor diameter
of said curved innermost transition region's ellipse perimeter.
[0044] In these exemplary versions, it may be further advantageous
to locate an outermost point of the radial slit arranged at a
radial distance from the outer shell of the rotor pole, the value
of which preferably lies between 0.6-0.7 mm (in order to bear the
12000 rpm with this rotor size). This arrangement may be stated
alternatively by indicating that said radially-outermost edge
section of said radially-extending longitudinal slot has a
radially-maximal extent spaced in the range of 0.6-0.7 mm from an
outer periphery of said at least one salient pole.
[0045] Further according to the invention, therefore in each case
an oblique cross-piece is provided between adjacent recesses (e.g.
between magnet pockets and flux barriers). Thereby, the
cross-pieces with the greatest stresses are stressed more strongly
to tension and less to bending. This results in a reduced notch
stress, whereby the risk of fracture of the cross-pieces is
significantly reduced. It is additionally expedient if the oblique
cross-pieces are configured to be as narrow as possible, in order
to thereby at the same time make possible a magnetic saturation
thereof more quickly, which in turn increases the performance of
the motor, as the magnet mass which is used can be utilized more
effectively.
[0046] Thus, in further developments, the invention may
advantageously include a rotor piece having a central axis, and
having a radial extent from said central axis. A first magnet
pocket recess is disposed in said rotor piece and transversely to a
radius of said rotor piece. This magnet pocket recess has a major
axis coinciding with a chord segment of a rotor circle delineated
by said radial extent. The magnet pocket recess has a
radially-outer top wall and a radially-inner bottom wall. It also
has a first end closing between said radially-outer top wall and
said radially-inner bottom wall, as well as a second end closing
between said radially-outer top wall and said radially-inner bottom
wall. A first flux barrier recess is located proximate to said
first end and is separated from said first end by a first oblique
crosspiece lying obliquely at an angle in the range of
10.degree.-50.degree. relative to a radius of said rotor piece that
passes through a center of said magnet pocket recess, said first
flux barrier recess having a respective upper wall and a respective
lower wall. A second flux barrier recess is located proximate to
said second end and is separated from said second end by a second
oblique crosspiece lying obliquely at an angle in the range of
10.degree.-50.degree. relative to a radius of said rotor piece that
passes through a center of said magnet pocket recess. This second
flux barrier recess has a respective upper wall and a respective
lower wall. A pocket recess first outer transition region lies
between said radially-outer top wall and said first end. A pocket
recess first inner transition region lies between said
radially-inner bottom wall and said first end. A pocket recess
second outer transition region lies between said radially-outer top
wall and said second end. A pocket recess second inner transition
region lies between said radially-inner bottom wall and said second
end. A first flux barrier upper transition region lies between said
first flux barrier respective upper wall and said first oblique
crosspiece. A first flux barrier lower transition region lies
between said first flux barrier respective lower wall and said
first oblique crosspiece. A second flux barrier upper transition
region lies between said second flux barrier respective upper wall
and said second oblique crosspiece. A second flux barrier lower
transition region lies between said second flux barrier respective
lower wall and said second oblique crosspiece. Each of said
transition regions preferably has a respective profile shape at
least approximately in a respective form of a respective curve of
second order. As a variation, each transition region's profile
shape may include a respective profile shape selected from the
group consisting of an elliptical profile, a parabolic profile, and
a higher-order polynomial profile; or, each transition region's
profile shape is a respective elliptical profile. Within these
developments of the invention as well, it should again be
understood, as previously referred to, that the rotor piece may
advantageously be produced from an iron-cobalt alloy.
[0047] In a preferred exemplary version, the radially outwardly
lying recesses have a ham- or kidney-like contour for an increased
deflection or respectively a concentration of magnetic flux lines
in radial direction.
[0048] In further developments, the invention may advantageously
include an outer magnet pocket recess disposed in said rotor piece
and transversely to a radius of said rotor piece, this outer magnet
pocket recess having a respective major axis parallel to the major
axis of the first magnet pocket recess. This outer magnet pocket
recess has a respective radially-outer top wall and a respective
radially-inner bottom wall. It also has a respective first end
closing between its respective radially-outer top wall and its
respective radially-inner bottom wall, as well as a second end
closing between its respective radially-outer top wall and its
respective radially-inner bottom wall. A first radially outwardly
lying recess is located proximate to said first end, this first
radially outwardly lying recess having a ham-like or kidney-like
contour. A second radially outwardly lying recess is located
proximate to said second end this second radially outwardly lying
recess has a ham-like or kidney-like contour. As will be readily
understandable, in advantageous variations, there may be: an outer
magnet pocket recess first outer transition region between said
outer magnet pocket recess radially-outer top wall and said outer
magnet pocket recess first end; an outer magnet pocket recess first
inner transition region between said outer magnet pocket recess
radially-inner bottom wall and said outer magnet pocket recess
first end; an outer magnet pocket recess second outer transition
region between said outer magnet pocket's radially-outer top wall
and said outer magnet pocket's second end; and, an outer magnet
pocket recess second inner transition region between said outer
magnet pocket's radially-inner bottom wall and said outer magnet
pocket's second end. Each of these outer magnet pocket's transition
regions may advantageously have a respective profile shape at least
approximately in a respective form of a respective curve of second
order. As shall be further readily understandable, in variants,
each respective transition region of said outer magnet pocket's
transition regions may advantageously include a respective profile
shape selected from the group consisting of an elliptical profile,
a parabolic profile, and a higher-order polynomial profile. Or, as
a variant, each transition region's respective profile shape may be
a respective elliptical profile.
[0049] A HSM (or CSM) with the rotor of plates of a cobalt/iron
alloy with flux barriers which are rounded in the notches
elliptically, or approximately elliptically, or respectively
according to a curve of second order, therefore creates a
surprising improvement in power density per space or per weight,
which is an important criterion in electric car construction for
vehicle drives.
[0050] In aspects, the invention also seeks improvement of the CSM
emergency running properties by increasing the reluctance, by
providing improved solutions via which the above disadvantages of
the prior art in the case of current-energized synchronous motors
(CSM) may be significantly reduced or eliminated. The
current-energized synchronous motor is further developed so that it
can produce a significant torque for driving a vehicle in emergency
operation without energizing. Thus, in aspects the invention
therefore significantly increases the torque without energizing by
current (reluctance moment) in the case of the current-energized
synchronous motor (CSM).
[0051] In versions, there is at least one selective magnetic flux
barrier, particularly in the form of a radial slot, provided along
the main axis of the rotor pole for increasing the reluctance
moment in each rotor pole. According to a further development, the
rotor poles are preferably in the form of salient poles. Such flux
barriers increase the magnetic resistance for flux lines in the
q-axis (quadrature axis) and thus effect an increase in the
reluctance.
[0052] Considering the technical preconditions for an improvement
in the CSM, against the background described previously, the
conventional current-energized synchronous motor was used as a
starting point and an object was to further develop it for vehicle
drives. It was found that the following important preconditions are
essential for improving the emergency running properties of the
current-energized synchronous motor: [0053] a magnetic barrier
along the main axis or d-axis of the rotor pole, which [0054]
greatly reduces the inductance of the transverse axis (Lq) but
which [0055] leaves the inductance of the main axis (Ld) at its
originally high value, with the result that [0056] a large increase
in the Ld/Lq ratio, the reluctance, occurs, and, the torque is
increased several times, for example by a factor of four, without
energizing.
[0057] Further considerations included the reduction of the
requirement for strategic raw materials. After long experience in
this area, and after overcoming the abovementioned prejudice, it
was also recognized that the CSM offers the technically most
advantageous possibility for automobile manufacturers for
protecting themselves from the price dependence in the case of
expensive high-performance magnetic materials, the so-called rare
earth element magnets (REE magnets), for hybrid and electric
vehicles.
[0058] Versions of current-energized synchronous motors that were
improved according to versions of the invention with regard to
their emergency running properties are outstandingly suitable as a
main drive motor, owing to their system properties. If a series
manufacturer substitutes the previously generally used permanent
magnet synchronous motor having buried magnets (IPM) by a
current-energized synchronous motor, any price trend or shortage of
the REE raw materials has no effect for the series
manufacturer.
[0059] To increase suitability of the CSM as a main drive, the
reluctance moment of the current-energized synchronous motor (CSM)
may be significantly increased in the absence of the energizing by
employing a selective magnetic flux barrier, for example in the
form of a radial slot in the rotor pole.
[0060] Such an emergency torque is a very major advantage in the
use as a main vehicle drive--but may be unimportant in certain
circumstances in the case of other applications. If for any reason
energizing power cannot be transmitted to the energizer windings of
the rotor, the level of the torque obtained from the reluctance
determines the system properties in emergency operation. The cause
of the absence of the energizer power might be, for example, a
failure of the rotor current controller, a short-circuit, a break
in the electric supply cables, or damage to the slip rings.
[0061] Thus, according to versions of the invention, the reluctance
moment of the current-energized synchronous motor itself plays a
very important role in vehicle drives, especially in emergency
situations when, for the abovementioned reasons, the vehicle
necessarily stands, for example, on a railway track or on
carriageways with heavy traffic. In such situations, the reluctance
moment of the current-energized synchronous motor according to the
invention makes it possible to move out of the danger area in order
to approach a safe position.
[0062] However, with the traditional current-energized synchronous
motor, without the reluctance barriers according to the invention,
this was not possible because, as mentioned above, the available
emergency torque had to be classed as insufficient after the
absence of the electrical energizing.
[0063] Considering the ready manufacturability of the invention
without narrowing of the basic properties of a CSM, in versions,
the invention is simple to produce by providing the rotor lamellae
with a slot-like recess by punching. Smaller webs may therefore
remain as connecting bridges in order to give the rotor the
necessary intrinsic strength. In a further development of the
invention, these mechanically indispensable connecting bridges are,
according to the invention, saturated by means of relatively small
permanent magnets. The required quantity of magnets corresponds to
about 10% of the magnet mass of a hybrid-energized (energized both
electromagnetically and by permanent magnets) synchronous motor
(HSM) of the same size and about 6% of the permanent magnet
synchronous motors of the same size.
[0064] The premagnetized permanent magnets are simply pushed into
the prepared "pockets" of the flux barriers (slot sections).
Without this measure, the flux barriers alone would work only after
saturation of the connections with the transverse flux, which
however is undesired, and would thereby give a smaller increase in
reluctance and thus a lower emergency torque.
[0065] Reference in this specification to "one embodiment," "an
embodiment," "one version," "a version," "one variant," and "a
variant," should be understood to mean that a particular feature,
structure, or characteristic described in connection with the
version, variant, or embodiment is included in at least one such
version, variant, or embodiment of the disclosure. The appearances
of phrases "in one embodiment", "in one version," "in one variant,"
and the like in various places in the specification are not
necessarily all referring to the same variant, version, or
embodiment, nor are separate or alternative versions, variants or
embodiments mutually exclusive of other versions, variants, or
embodiments. Moreover, various features are described which may be
exhibited by some versions, variants, or embodiments and not by
others. Similarly, various requirements are described which may be
requirements for some versions, variants, or embodiments but not
others. Furthermore, as used throughout this specification, the
terms `a`, `an`, `at least` do not denote a limitation of quantity,
but rather denote the presence of at least one of the referenced
item, and the term `a plurality` should be understood to denote the
presence of more than one referenced items.
[0066] Further advantages, variants and details of versions the
invention are given below in the description of the Figures and in
the accompanying detailed description.
BRIEF DESCRIPTION OF THE DRAWINGS
[0067] The invention is illustrated in the attached drawings with
reference to exemplary versions of hybrid synchronous motors and
current-energized synchronous motors according to the
invention.
[0068] FIG. 1 shows a cross-section of a version of
current-energized synchronous motor, with magnetic flux lines;
[0069] FIG. 2 shows a diagram of an embodiment of the synchronous
motor according to FIG. 1 as a result of the design process;
[0070] FIG. 3 shows a further side view of the rotor of the
synchronous motor according to FIG. 1 without magnetic flux
lines;
[0071] FIG. 4 shows a view of an exemplary version of the rotor
geometry;
[0072] FIG. 5 shows a view of a part II in FIG. 4, on an enlarged
scale;
[0073] FIG. 6 shows a view of a part III in FIG. 5, on a
proportionally enlarged scale;
[0074] FIG. 7 shows a partial view of another version of the rotor
geometry (60.degree. sector);
[0075] FIG. 8 shows yet another version of the rotor geometry for a
HSM, in this view with six rotor poles;
[0076] FIG. 9 shows a partial view VI in FIG. 8, on a
proportionally enlarged scale;
[0077] FIG. 10 shows a partial view VII in FIG. 9, on a
proportionally enlarged scale; and,
[0078] FIG. 11 shows a further partial view in FIG. 9, on a
proportionally enlarged scale.
DESCRIPTION OF EXEMPLARY VERSIONS OF THE INVENTION
[0079] Cross-Section of the Rotor and Stator
[0080] FIG. 1 schematically shows a cross-section of a working
example of a current-energized synchronous motor 1 according to the
invention, which is formed in particular for vehicle drives. The
synchronous motor 1 is provided with an external stator 2 and an
internal rotor 3. The stator 2 is provided in a manner known per se
with grooves for a distributed winding 2A.
[0081] Rotor Geometry
[0082] In the working example depicted, the rotor 3 has a six-pole
design (a two-pole, four-pole, eight-pole, etc., rotor is
optionally also possible). FIG. 1 illustrates the rotor 3 having
salient poles 4 whose pole shank and pole shoe are designated by 5
and 6, respectively. One energizer winding 7 each which is arranged
along the pole shank 5 and is represented as a cross-sectional area
in the diagram is coordinated with each of the rotor poles 4 in a
manner known per se.
[0083] Flux Barriers Along the Main Pole Axis
[0084] According to the invention, a completely novel rotor
geometry is presented. There is provided at least one selective
magnetic flux barrier, preferably in the form of a slot 8 along the
main axis 4A of the rotor pole 4 in each rotor pole 4 for
increasing the reluctance moment of the current-energized
synchronous motor 1. The slots 8 acting as a flux barrier are
preferably formed in the pole shanks 5 as central and radial
longitudinal openings having substantially parallel lateral
surfaces 9 (cf. FIG. 2), although the possibility of selective
deviations from strict parallelism should be understood.
[0085] Regarding the more important dimensions and the mutual
arrangement of the slot 8 and of the rotor pole 4, it is evident in
the case of this working example in FIG. 2 that the relatively
narrow radial slot 8 has a length L and a width B. According to
experiments by the inventors, in this version, the length L of the
slot 8 is from 3/4 to of the rotor radius R minus the radius 3A of
the drive shaft 12, and the width B of the slot 8 is between 1/10
and 1/15 of the shank width W.
[0086] When viewed in the radial direction, the outermost point 10
of the slot 8 is arranged a distance 11 from the outer pole surface
of the pole shoe 6 in such a way that a cap nut fitting the
threaded bolt therefore does not project beyond the outer shank
pole surface. The pole caps and the rotor lamellae packet are
joined by the threaded bolts, as connectors, to give a whole
unit.
[0087] Presaturation of Webs and Bridges in Flux Barriers
[0088] In a preferred embodiment of the current-energized
synchronous motor according to the invention as shown in FIG. 2, a
relatively small permanent magnet 13 (e.g. altogether 0.2 kg
magnet/50 kW rated power) is arranged in the radially inner section
of the slot 8 (pocket). The already premagnetized solid-state
magnet 13, which is itself a flux barrier, is dimensioned so that
its flux lines produced by it are just sufficient to saturate the
webs 14 in the flux barrier which are provided for structural
reasons but are magnetically conductive per se. The webs 14
presaturated in this manner then represent a high resistance for
each further magnetic flux. They therefore behave like an extension
of the slot 8 with respect to the useful flux during operation.
Their magnetic conductivity which is troublesome for this
application is eliminated by the inserted magnet 13.
[0089] The web 14 is mechanically advantageous for taking up the
resultant centrifugal forces or the compressive forces of the shaft
fit between shaft and rotor 3. It is designed precisely according
to strength considerations and tailored to the application.
[0090] The intended saturation of a mechanically motivated break in
the flux barrier in the quadrature axis (q-axis in FIG. 2) of the
shank pole motor 1 with a permanent magnetic 13 which is introduced
exclusively for this purpose therefore constitutes a fundamental
further development of the invention which can also be used in
certain circumstances in electric drives regardless of the
application described. In this respect, the invention is therefore
not limited to a CSM.
[0091] Wherever lamellar bridges are required for strength reasons
but magnetic flux barriers are more advantageous such magnets can
be used for eliminating the magnetic conductivity of the lamellar
bridges.
[0092] Joining Methods
[0093] Although it was not depicted in detail, the rotor 3 may also
include traditional lamellae, end plates and a connector 15 (for
example, connecting bolts) which connects rotor lamellae packet and
end plates to one another to give one piece (in FIGS. 1 and 3, only
a sectional picture thereof was shown). According to the present
invention, the connector 15 should preferably be arranged within
the slot 8 acting as magnetic flux barrier. The connecting bolts of
the connector 15 are inserted into the rotor lamellae and end
plates through holes 16 which in the embodiment illustrated, as
viewed in the radial direction, practically form the outer end of
the slots 8 acting as a flux barrier. In this case, the holes 16
may have a diameter of about 5.2 mm in order to receive a, for
example, approximately 5 mm thick clamping bolt.
Improvements Compared with the Prior Art
[0094] Increase in the Reluctance
[0095] With the flux barriers, the reluctance increases
significantly according to the invention, and with it, the
available reluctance moment increases by the factor three to four
in comparison with embodiments without flux barriers.
[0096] Performance Data of the Working Example Shown
[0097] In an investigated machine with 85 Nm nominal moment,
experiments by the inventors have shown that an emergency moment of
72 Nm, i.e. almost 90% of the nominal moment, may be realized with
the proposed reluctance barriers. Without the reluctance barriers
according to the invention, a comparable rotor, which would be
manufactured according to the prior art, could generate only about
20 Nm emergency moment without energizing, which is too little for
its use as a main drive, even in emergency operation.
[0098] The CSM shown can output 320 Nm in short-term operation and
with intact energizing. If it is additionally equipped according to
the invention with the proposed reluctance barrier, it also has
substantially improved emergency properties at lower additional
costs. The originally advantageous system properties of the CSM
are, however not adversely affected by the reluctance barrier
because the CSM according to the invention, too, can be operated
with a very high power factor in all operating states and can
output a constant power in a wide speed range (greater than 1:5) at
very high efficiency.
[0099] Summary of the effects, considering FIGS. 1-3: In the
preferred current-energized synchronous motor according to FIGS.
1-3, the ratio of the inductance of the longitudinal axis (d-axis)
to the inductance of the transverse axis (q-axis in FIG. 2) is
accordingly increased well beyond the normal degree of a
conventional salient-pole machine as a result of the introduction
of a flux barrier running along the d-axis (i.e. a slot 8), the
mechanically required residual width in the vicinity of the axis
preferably being completely saturated by a permanent magnet 13
introduced into this flux barrier with the result that the effect
of the flux barrier is both displayed in the region of the bridges
and continues through the web to the axis.
[0100] FIG. 4 shows diagrammatically the view of another example
version of the rotor 21 (without rotor shaft), which is provided
for a current-excited synchronous motor (CSM), for example suitable
for vehicle drives. In this example version, the rotor 21 is a
six-pole type; however, if applicable, two-pole, four-pole,
eight-pole, etc., rotor geometries also lie within the scope of the
invention. The rotor poles are designated in FIG. 1 by label
22.
[0101] This rotor 21 is illustrated in FIG. 4 as a salient pole
rotor, wherein each of the rotor poles 22 has a pole shank 23 and a
pole shoe 24. Each rotor pole 22 is provided in a manner known, per
se, with an exciter winding 25, which is arranged around the pole
shank 23. The cross-section of the exciter winding 25 is
illustrated only diagrammatically and hatched in FIG. 4.
[0102] The rotor 21 in this version includes a stack (bundle) of
uniform rotor plates 26 that are combined in a manner known per se,
for example glued, welded, or connected by a positive fit (not
illustrated).
[0103] In FIG. 4 it may be seen that the lamination changes here
from a closed ring element--technically designated as hub 27--to
six rotor poles 22 connected externally thereon, that are
respectively wound around with the wire (for example, copper wire)
of the exciter windings 25. A central opening of the rotor 21 to
receive the rotor shaft (not illustrated) is designated by 28.
[0104] In each rotor pole 22, a radial recess acting as a flux
barrier is provided, i.e. a slit 29 along a pole axis 30. The
recesses or slits 29 are configured here in the rotor poles 22 as
central longitudinal openings with substantially parallel edges or
side faces 31 (FIGS. 4 and 5).
[0105] The dimensions and the relative arrangement of the slit 29
in a rotor pole, or respectively the rotor poles 22 of this example
version itself are to be seen in FIGS. 4 and 5. Through the present
invention, a novel rotor geometry is indicated and, optimized
mechanically.
[0106] The radial slit 29 in the rotor plate 26 is configured
elliptically at least at its origin, i.e. at the radially inner end
32 of the slit 29 in its transition region 33, i.e. with a
continuous increase of the distances 34a . . . 34g from an
intersection O of a main axis 36 and a secondary axis 37 of an
ellipse 35, in order to reduce the notch stresses--as greatly as is
practically possible--in these transition regions 33 (FIG. 6). The
ellipse 35 therefore lies with its main axis 36 ideally arranged
tangentially to the high radial stresses, which occur both with
high pressure, necessary for torque transmission at high rotation
speeds, and also with high centrifugal forces, because both forces
attempt to widen the rotor radially outwardly. Thus, the ellipse 35
lies approximately transversely to the pole axis 30. In FIG. 6, the
recess or slit part 29A has three transition regions 33: from the
left-hand side face 31 (edge) over the radially deepest point P up
to the right-hand side face 31 (edge).
[0107] In this version, the continuous increase of distances
34a-34g is configured as part of the ellipse 35 (FIG. 6). The full
ellipse 35 is only illustrated by dot-and-dash lines in FIG. 6. In
the inner end 32 (front face) of the radial slit 29, the ellipse 35
is therefore arranged tangentially, i.e. with its main axis 36
perpendicularly to the pole axis 30 (FIG. 5).
[0108] In the illustrated example version, the main axis 36 of the
ellipse 35 is preferably longer by 40-60% than the width 38 of the
slit 29. The secondary axis 37 of the ellipse 35 is preferably
shorter by 70-80% than the width 38 of the slit 29. In the example
version according to FIG. 6, the width 38 of the slit 29 is
selected at approximately 2.5 mm, the main axis 36 at approximately
3.6 mm and the secondary axis 37 of the ellipse 35 at approximately
1.4 mm.
[0109] According to the calculations and considerations carried
out, through this configuration an effective, harmonious deflection
of the stresses takes place in the transition regions 33. This
continuous increase in distance as a condition could, however, also
be fulfilled according to the invention--as had already been
mentioned above--in addition to the ellipse 35, by means of
parabolae (quadratic function), hyperbolically, as polynomials of
higher order or by two or more radii, continuing into each other
tangentially, of circles of different diameter (approximation to
the ellipse).
[0110] Such approximations to the ellipse may be seen, for example,
in FIG. 9, and namely in the radially outer roundings of the flux
barriers, which according to FIG. 9 are composed of three circles
in each case with different radii, while the comparable roundings
according to FIG. 7 are circular or may be configured purely
elliptically. It is evidently crucial that the transition does not
take place angularly or in the form of a single circle (with
constant radius), but rather with a continuous increase of the
distances 34a . . . 34g from the point O.
[0111] In considering also other curves of second order, by
definition as according to an ellipse (hyberbola or parabola), a
requirement of a "distance gradient" is also specified, i.e. the
requirement of a continuous change of the distances 34a . . . 34g
of the individual ellipse points from the ellipse centre point O
(FIG. 6).
[0112] As may be seen in FIGS. 4-6, in this version the radial slit
29--viewed in its longitudinal axis (which coincides here with the
pole axis 30)--is divided into two parts by a bridge or cross-piece
39, wherein the radially inner first slit part 29A is configured to
receive a permanent magnet 50 as additional flux barrier (see also
FIG. 4), and the radially outer second slit part 29B as reinforced
air gap-flux barrier.
[0113] Using the teachings according to the invention, preferably
the following parts may be configured elliptically and/or
parabolically: [0114] the radially inner end 32 of the slit 29, or
respectively of the first slit part 29A, [0115] the respectively
inner end 32 or respectively 50 of both slit parts 29A and 29B,
[0116] the radially outer end 41 of the first slit part 29A or of
the slit parts 29A and 29B; [0117] likewise, an ellipse is also
conceivable and used expediently at an outermost point 46 of the
second slit part 29B.
[0118] In the present preferred example version, not only these
ends 32, 40, 41 of the slit parts 29A and 29B of rotor poles 22,
but at all transitions of the rotor geometry of opening or
respectively recesses to the full material are configured with a
distance gradient, in particular elliptically, in order to further
reduce the centrifugal force-induced stresses in the rotor
plate.
[0119] In the version according to FIG. 5 a width of the bridge 39
was designated by 42. The value of the width 42 of the bridge 39 is
selected here at approximately 1.2 mm, and a length 43 of the inner
first slit part 29A at approximately 15.5 mm, and a length 44 of
the radially outer second slit part 29B at approximately 12.5
mm.
[0120] The region of an outer end 45 of the second slit part 29B is
widened here circularly with a radius R1 (FIG. 5), the value of
which here is about 2.6 mm. The outermost point 46 of the slit part
29B is arranged from an outer shell 47 of the pole shoe 24 at a
radial distance 48, the value of which in this case is
approximately 0.7 mm. In this example version, the maximum rotor
radius R was selected at 82 mm (FIG. 4) and the diameter of the
opening 28 of the rotor 21 was selected at 85 mm.
[0121] In FIG. 5 it may also be seen that as a rounding or curve in
the transition regions 33, the same ellipse 15' is used at the
outer end 41 of the first slit part 29A and at the inner end 40 of
the second slit part 29B, the secondary axis 37' of which, however,
is smaller (only approximately 1.0 mm) than the secondary axis 37
of the ellipse 35 at the inner end 32 of the first slit part 29A.
The ellipses 35' have the same main axis 36 as the ellipse 35.
[0122] In FIGS. 5 and 6, the ellipses 35 or respectively 35' are
connected with the side faces 31 (edges) of the slit 29 by a radius
49, the value of which was selected here at approximately 5.0 mm.
In FIG. 4 a radial distance between the opening 28 and an innermost
point P (see also FIG. 6) of the slit 29 was designated by 51. The
distance 51 in this case has a value of 10.0 mm.
[0123] The rotor geometries according to the invention open up new
possibilities for the motor designers, which are based on the
following findings:
[0124] As the prior art offers no basic principles for a motor type
of the current-excited synchronous motor in this structural and
output size, extensive tests, calculations and modelling were
carried out by the inventor for the realization of the above
concepts. In the first step, the cylinder press fit between rotor
shaft and plate stack of the rotor was tested. Particularly in the
upper rotation speed range 8000 to 12000 rpm, a distinct difference
in operating behaviour was able to be established here when
compared with previous plate stacks as in the hybrid synchronous
motor or in an IPM (motor excited by interior permanent
magnets).
[0125] In the comparison of these two laminations--with regard to
the joining pressure--a reduction of about 70% was able to be
established at the maximum rotation speed. As the widening of the
hub 27 with respect to the shaft--owing to the greater median
diameter and the greater centrifugal force connected
therewith--increases more rapidly, with an increasing rotation
speed the interference fit, and hence the joining pressure,
decreases. Therefore, according to the invention with the geometry
of the current-excited synchronous motor an increase of the
interference fit is definitively preferred, in order to thereby
prevent a lifting of the rotor hub, even at high rotation speeds.
This lifting must be prevented in order to ensure the torque
transmission between rotor shaft and plate stack in all operating
situations. For this reason here according to the invention the
identical joining pressure between rotor shaft and hub is to be
aimed for as in closed laminations according to the prior art
known, per se, similar to FIG. 7.
[0126] Based on these findings according to the invention, the
geometry of the rotor plate 26 was able to be dimensioned more
objectively with regard to stability. In order to prevent a failure
of the final rotor stack in operation, the necessary components
were tested with regard to stresses and were successfully adapted
geometrically.
[0127] The geometry of the proposed rotor plate 26 also influences
very positively the lifting behaviour of the rotor 21 from the
shaft. With a maximum rotation speed of 12000 rpm, a minimum
joining pressure of 6122 MPa, and a maximum joining pressure of
14862 MPa--according to tolerance position--there were measured in
a prototype the lifting of the rotor hub from the rotor shaft
employing the rotor geometry according to the invention. The
significant increase of the rotation speed lower limit for the
lifting of the rotor hub from the machine shaft constitutes an
original, previously unrealized, and very advantageous technical
effect.
[0128] The dimensioning of the lamination (by use of the Finite
Element Method) takes place through an analysis on the model of the
60.degree. segment, which was already used for the calculations of
the cylinder press fit. The recess (the radial slit 29) is situated
in the pole axis, which serves to increase the reluctance moment of
the available torque without exciting current. This characteristic
is of crucial importance for the CSM for obtaining the emergency
operating characteristics (in vehicle drives) in the case of
fault.
[0129] Viewed physically, this flux barrier separates from each
other the two magnetic flux lines, with run in opposite directions,
and prevents too great a phase shift between the current axis and
the field axis. Therefore, the torque which is produced may also
nevertheless be kept at the nominal torque without a current supply
of the rotor winding (for example, also in an emergency
operation).
[0130] For this reason, the dimensioning of this flux barrier is
accorded increased attention. Ideally, the pole would be completely
separated through in the vertical axis. As this is not possible,
however, for mechanical reasons, the flux barrier becomes as large
as possible and the remaining mechanical connections, which are
designated as "magnetic bridges", are preferably saturated
magnetically by a permanent magnet or by the basically present
magnetic flux. As soon as the bridges are saturated, they act as
flux barriers. In this way, a complete separation of the two
regions is achieved with regard to the magnetic flux.
[0131] Tests showed that without the present invention, with a
standard dimensioning, at 12000 rpm in the rotor plate stress peaks
are reached with respect to the comparison stress according to
MISES of over 870 MPa.
[0132] The parameters, influencing each other reciprocally, formed
a vicious circle which is broken only by the present invention.
Through the invention, it becomes possible for the first time to
offer CSMs in the same overall size as IPMs with at least the same
performance and with an identical rotation speed range.
[0133] In the region of the flux barrier (of the radial slit 29),
enormous notch stresses occurred at the geometric transitions from
the horizontal into the vertical. With conventional roundings,
stress peaks additionally occurred at the tangential transitions.
Through the invention, and factually confirmed by variational
calculus, the stresses were able to be reduced to a minimum by
geometric alterations, wherein the shape of an ellipse ultimately
produced the transition with the least stresses. This is evidently
to be attributed to the continuous increase of the distance towards
the notch.
[0134] The ellipse 35 is therefore (FIGS. 4-6) to be configured
"recumbent", i.e. the main axis 36 perpendicular to the slit 29 or
respectively tangentially at the end of the radial slit 29. By
definition, notch stresses are a concentration of stresses as a
result of force deflections on notches and projections. According
to the invention, the force deflection can be configured more
"harmoniously", which is an important advantage of the invention.
The stresses in the lamination are dominated by the radial stresses
in the peripheral direction and these undergo a deflection in the
region of the recess (slit 29). Through the ellipse 35 with its
continuous distance increase, this force deflection takes place
particularly harmoniously.
[0135] FIG. 7 illustrates a partial view of a second version of the
geometry having a rotor plate 26 of a rotor 21 for a HSM. Here, the
rotor plate 26 is provided with recesses 29 as flux barriers,
wherein a first group of the recesses 29 is configured, with
respect to the diameter, as approximately radial slits. Another
group of the recesses 29, however, is configured as tangential
slits (magnet pockets) with in each case a permanent magnet 50. In
this version, mechanically highly stressed transition regions 33 of
all recesses 29 are configured elliptically.
[0136] Between the adjacent recesses 29 in each case a cross-piece
52 is provided, the width of which is to be configured as narrow as
possible for saturation purposes and is to withstand the
centrifugal forces mechanically. As may be seen from FIG. 7, in
this version the cross-pieces 52 have a parallel position to the
pole axis 30. A center line of the cross-piece 52 is designated in
FIG. 7 by reference number 54.
[0137] FIGS. 8-11 illustrates a third preferred version of the
geometry according to the invention of a rotor plate 26 of a rotor
21 for a HSM, wherein FIG. 8 is a complete view of the rotor plate
26, FIG. 9 a partial view VI in FIG. 8 on a proportionally enlarged
scale, and FIGS. 10 and 11 is/are each a partial view in FIG. 9, on
a proportionally likewise enlarged scale.
[0138] The plate geometry for the HSM according to FIGS. 8-11
differs from the version according to FIG. 7 substantially in that
here the center lines 54 of the cross-pieces 52 between the
adjacent recesses 29 in the rotor plate 26 are configured obliquely
to the pole axis 30, preferably at an angle 53 of approximately
10-50.degree., in particular 30.degree..
[0139] The reasons for the inclination of the cross-pieces 52
according to the invention may be summarized as follows: [0140] At
high rotation speeds, powerful centrifugal forces impinge and draw
the cross-pieces 52 in the direction of the pole axis 30, because
in radial direction of the pole axis, owing to the material
accumulation by permanent magnets and the additional pole iron
between the permanent magnets the greatest centrifugal forces occur
in this direction; through the inclination according to the
invention it is achieved that with the greatest stresses, the
cross-pieces 52 are mostly stressed in longitudinal direction to
tension and are stressed as minimally as possible to bending
stress, in order to thus prevent signs of material fatigue in the
cross-pieces 52 and hence to reduce the risk of fracture; [0141]
The local notch effect at the force deflection sites is reduced by
the use of the ellipses 35; [0142] The stresses in the cross-pieces
52 can be reduced continuously with an increasing inclination.
[0143] Through the inclination of the cross-pieces 52, in
connection with the improved embodiments of the transitions
(ellipses), a symbiotic effect is produced, which reduces the notch
effect still further.
[0144] In versions of the present invention therefore, through the
oblique cross-pieces 52 and the special, in particular elliptical
transitions of the recesses 29, a significant reduction of the
mechanical stresses may be achieved in the rotor plate 26.
[0145] Through this stress reduction, inter alia the following
conclusions result: [0146] the oblique cross-pieces 52 can be
configured distinctly narrower, which is connected with a saving on
material with regard to magnet material and hence with a certain
saving on weight, or [0147] the oblique cross-pieces 52 can be
configured distinctly narrower and with an unchanging magnet mass
the performance of the machine increases with regard to torque and
output, or [0148] the security of the rotor 21 or respectively of
the machine (with regard to the maximum rotation speed) can be
distinctly increased.
[0149] FIG. 11 illustrates a further partial view in FIG. 9,
wherein the special ham- or kidney-like shape of the two radially
outermost recesses 29 of the rotor plate 26 (alongside the smallest
magnets) may be seen in a proportionally enlarged scale. All the
curve shapes of all radially outwardly lying recesses 29 comprise
here either a part of an ellipse 55 lying flat and approximately
tangential to the periphery of the rotor (the full ellipse 35 is
only illustrated in dot-and-dash lines in FIG. 11), or of at least
two radii, running into each other, with different sizes, so that
practically an ellipse is approximated. Therefore, for example, to
the right and left, two smaller radii could be used and in the
centre, pointing radially outwards, one larger radius could be
used.
[0150] In FIG. 11 it may also be observed that here a radius R2 or
respectively R3 is connected in each case to the ellipse 35 on both
sides, which radii are connected with each other by the lower
radius R4. As has been described more extensively above, the
cross-pieces 52 also alongside the smallest magnets 50 have a
special oblique arrangement in this version, i.e. the centre line
54 of the cross-pieces 52 between the adjacent recesses 29 in the
rotor plate 26 stands at an angle 53 obliquely to the pole axis 30,
the value of which is approximately 10-50.degree., in particular
15-30.degree..
[0151] Through the curve shape according to the invention (ham- or
kidney-like shape with elliptical end regions) of the recesses 29
(FIG. 11)--apart from the advantageous stress reduction against
fracture--it is achieved that they form a "magnetic lens"
(focussing lens on magnetic flux lines M), and they bundle or
respectively deflect the magnetic flux lines M also from the
radially outermost small magnet approximately in radial direction
(FIG. 11). On the other hand, the oblique cross-piece shape reduces
the extremely high notch stress, because the force deflection is
reduced.
[0152] As a result, the HSM with, for example reduced magnet mass,
may be lighter, more stable with regard to mechanical stress and
has a greater torque, owing to the magnetic lens in the outer
region. (The structure according to FIG. 7 may be less preferred in
this respect owing to these differences.)
[0153] It is also to be mentioned that at least the rotor plates 26
according to the present invention (if applicable, however, also
the stator plates) are preferably constructed from an iron-cobalt
alloy. Thereby, further increase in performance and insensitivity
to temperature, and less lost heat of the electric motor can be
achieved. With this alloy, preferably approximately 50% cobalt with
approximately 50% iron may be alloyed.
[0154] With such a "cobalt plate", surprisingly even about 40% more
torque is produced with otherwise identical machine design of a HSM
(compared with a HSM with conventional iron plates). An ideal
structure is therefore found especially for electric high
performance racing engines. Therefore, this measure is also to be
regarded as new and significant.
[0155] If applicable, these iron-cobalt plates may also be
configured permanent-magnetically, which achieves the effect that
the magnetic fields produced by the permanent magnet (HSM) or by
the electromagnet (CSM) lead to a magnetization of the rotor plate
26. This does not play an essential role in the HSM. In the CSM, on
the other hand, this results in that also after the switching off
(failure) of the exciting current, nevertheless a rotor magnetic
field is present, which can still be used for torque generation. In
the stator, where the magnetic polarity changes, on the other hand,
preferably no permanently magnetic plates come into use.
[0156] As mentioned, the measure according to versions of the
invention, the use and broadening of the ellipse (or other curves
of second order) to other laminations, and preferably to all
transition regions of the recesses 29 is considered extremely
important in practice. According to versions of the invention, the
notch stresses in the rotor plate 26 in the HSM were even able to
be reduced by 25%, which is likewise a surprising effect of
versions of the invention.
[0157] The laminations of electric motors are definitely very
varied. In principle at least all transitions of the recesses 29
lying close to the shaft (close to the inner geometry) (transitions
stressed with high stresses) may be configured in this manner
according to the invention. This geometry could also even be used
to reduce bending stresses.
[0158] It is also emphasized, that the systematic reduction of
notch stresses preferably by ellipses in the transition regions 23
in the outer region, in addition to mechanical advantages also
brings magnetic advantages, and therefore a somewhat increased
efficiency, because thereby the magnetic short-circuits can be
significantly reduced in the outer region. The above reduction of
the magnetic short-circuit face (owing to the ellipses 35) in the
outer region of the rotor 21 and hence an increase in the
efficiency also belong to the overall aim of increasing the
performance and, simultaneously, improving stability of the
motor.
[0159] The version of rotor plate construction, with the ellipses
35 at the transition regions 33, in combination with the oblique
cross-pieces 52, makes possible significant reduction of the
stresses in the sites which are at risk of fracture (i.e. at
transitions of the cross-pieces 52 to the solid material of the
rotor plate 26). Tests confirmed that, through the proposed oblique
cross-pieces 52, the cause of stress can be significantly mitigated
and through the ellipse 35 the stress effect can be effectively
reduced; that through both measures, therefore, symbiotically, an
improvement of the rotor is produced in terms of the
objectives.
[0160] Although the rotor geometry may be linked with a slightly
increased production expenditure in regard to tools, the use of an
ellipse or parabola in the transition regions 33 of the recesses is
nevertheless categorically advisable in cases of application where
high demands are made with regard to stability.
[0161] It is also to be noted that the oblique cross-pieces 52 are
relatively longer. Therefore, with an oblique cross-piece 52 the
magnetic path is also somewhat longer and therefore its disrupting,
flux-deviating effect is somewhat reduced. The proposed oblique
cross-pieces 52 therefore offer a greater resistance to the
magnetic field and in such a way also act more quickly in a
saturated manner, i.e. "non-magnetically" for a further flux.
[0162] An even more important aspect, from a practical point of
view, of the use of the proposed oblique cross-pieces 52 is
observed in that the mechanical stresses decrease by 30% with the
inclination, and thereby: [0163] the oblique cross-pieces 52 may be
configured distinctly narrower, which is connected with a saving on
material with regard to magnet material and hence with a certain
saving on weight, or, [0164] the oblique cross-pieces 52 may be
configured distinctly narrower, and with unchanging magnet mass the
performance of the machine increases with regard to torque and
output, or, [0165] the security of the rotor, or respectively of
the machine (with regard to the maximum rotation speed) may be
distinctly increased.
[0166] Through the use of the present invention and its subsequent
analysis by means of the Finite Element Method with the ANSYS
software, based on the model of a 60.degree. segment, which was
also used for testing the cylinder press fit, it is found that the
slit can be provided without disadvantage, and serves there to
increase the reluctance moment--of the available torque in the
absence of exciting current.
[0167] This characteristic is of crucial importance to the CSM for
obtaining the emergency operating characteristics in the case of
fault, and is to be preferred for an electric car equipped
according to the invention. If, in addition, a permanent-magnetic
rotor plate were to be selected, this effect may be further
intensified.
[0168] This flux barrier separates from each other the two magnetic
flux lines, which run in opposite directions, and prevents too
great a phase shift between the current axis and the field axis.
Therefore, the torque which is produced can nevertheless be kept at
the nominal torque without current supply of the rotor winding,
which plays a very important role in electric cars without regard
to functional security.
[0169] Through the invention, the entire rotor stack changes, and
therefore the Hybrid Synchronous Motor (HSM) (and if
applicable--according to the use of the invention--also the
current-excited synchronous motor CSM). The invention therefore
offers an improved lamination which handles the high forces in the
rotor plate better than in the prior art, because due to the high
centrifugal forces with high angular speeds--in particular at
revolutions of about 12000 rpm--in operation the laminations are
intensively stressed.
[0170] Further versions, embodiments, or variants of the present
invention, and also combinations thereof, are also yielded to the
reader's conception within the framework of the scope of protection
according to the present disclosure and enclosed claims, for which
however, given the knowledge of imparted by the present disclosure
of the invention, an artisan in this art after reading or receiving
the teachings herein, needs no further technical information. Thus
in closing, it should be noted that the invention is not limited to
the abovementioned versions and exemplary working examples. Further
developments, modifications and combinations are also within the
scope of the patent claims and are placed in the possession of the
person skilled in the art from the above disclosure. Accordingly,
the techniques and structures described and illustrated herein
should be understood to be illustrative and exemplary, and not
limiting upon the scope of the present invention. The scope of the
present invention is defined by the appended claims, including
known equivalents and unforeseeable equivalents at the time of
filing of this application.
LIST OF REFERENCE LABELS
[0171] 1--motor [0172] 2--external stator [0173] 2A--distributed
winding [0174] 3--internal rotor [0175] 3A--radius [0176]
4--salient pole [0177] 4A--main axis of rotor pole [0178] 5--pole
shank [0179] 6--pole shoe [0180] 7--energizer winding [0181]
8--slot [0182] 9--lateral surfaces [0183] 10--outermost point
[0184] 11--distance from outer pole surface [0185] 12--drive shaft
[0186] 13--permanent magnet [0187] 14--web [0188] 15--connectors
[0189] 16--holes [0190] 21--rotor [0191] 22--rotor pole [0192]
23--pole shank [0193] 24--pole shoe [0194] 25--exciter winding
(cross-section) [0195] 26--rotor plate [0196] 27--hub [0197]
28--central opening (joint diameter) [0198] 29--recess/slit, or
contour section [0199] 29A--first slit part [0200] 29B--second slit
part [0201] 30--pole axis [0202] 31--side face/edges (recess/slit
29) [0203] 32--inner end (of slit or of first slit part 29A) [0204]
33--transition region [0205] 34a, . . . , 34g--distance from
intersection of the main--and secondary axis [0206] 35 and
35'--curve of second or higher order, preferably ellipse [0207]
36--main axis (of ellipse) [0208] 37 and 37'--secondary axis (of
ellipse 35 or 35') [0209] 38--width (of slit) [0210] 39--bridge
[0211] 40--inner end (of second slit part 29B) [0212] 41--outer end
(of first slit part 29A) [0213] 42--width (of bridge 39) [0214]
43--length (of first slit part 29A) [0215] 44--length (of second
slit part 29B) [0216] 45--outer end (of second slit part 29B)
[0217] 46--outermost point (of second slit part 29B) [0218]
47--outer shell (contour section of rotor pole) [0219] 48--radial
distance [0220] 49--radius [0221] 50--permanent magnet [0222]
51--distance [0223] 52--cross-piece [0224] 53--angle [0225]
54--centre line (of cross-piece) [0226] B--width [0227] L--length
[0228] W--shank width [0229] q--quadrature axis [0230] M--magnetic
flux lines [0231] O--intersection (of main and secondary axis of
ellipse) [0232] P--radially innermost point of recess/slit [0233]
R--rotor radius [0234] R1--radius (of second slit part 9B) [0235]
R2--radius [0236] R3--radius [0237] R4--radius
* * * * *
References